OpenGL extensions
Rendering tests
Cross platform

A very extensive list of details of all extensions available of your system, which OpenGL functions are implemented and more.
A core feature set check also show how well from OpenGL version 1.2 to 4.0 are implemented in your system.
More than 450 extensions reported and collected since 2000!

OpenGL 1.1 / 1.2 OpenGL 1.3

OpenGL Extensions Viewer has been suggested by
in the OpenGL technical FAQ (see 23.050) (**)
and by nVidia as Developer Resources.